Haptic display of space through portable navigation aids for the visually impaired: Spatial perception via touch is a primary compensation for the capabilities lost when vision is diminished, and the long cane arguably remains the most popular and effective navigation aid for the visually impaired. Forces and torques sensed through the handle of the cane are two of the most important cues through which users infer the layout of the environment. Surprisingly, these cues have not been explicitly incorporated into electronic travel aids, which have instead focused on auditory or vibrotactile coding of distance, neither of which is intuitively associated with the sensing of environmental layout.The goal is to utilize force and torque cues, which make the use of the cane so very intuitive in the first place, to effectively convey the layout of the environment beyond the reach of the cane. We will develop a novel class of electronic travel aids that utilize these cues, in conjunction with rangefinding sensors, to achieve this intuitive extension of discernible space. These devices can be used either as generalized navigation aids or in specific situations, such as for seeking out physical landmarks on the other side of a street to facilitate crossing. We will address force and torque cues separately in this study to determine their individual roles in spatial perception as applied to navigation as well as obstacle detection and avoidance. We will perform experiments and develop devices tailored to each of the two types of cues. Both types of devices will then be evaluated in a common set of tasks to facilitate comparisons. Since this research on electronic travel aids builds on principles derived from the most effective travel aid in use, it promises a significant enhancement of navigation capabilities of the visually impaired, with associated effects on independence and quality of life.